A tank type gas circuit breaker is so constructed that a sealed vessel is formed of a cylindrical tank, which is filled with an insulating gas such as sulfur hexafluoride (SF.sub.6) gas, and that an interrupting portion is included therein which is electrically insulate from the tank.
In a tank type gas circuit breaker of high voltage and large capacity, one interrupting set of fundamental structure is typically provided which is composed of two interrupting units connected in series. For still higher voltage classes, a plurality of interrupting sets of such fundamental structure are connected in electrical series.
For this reason, the length of the tank type gas circuit breaker in the direction of the switching operations of the interrupting units increases with the interrupting capacity thereof. By way of example, the length of a tank type gas circuit breaker provided with four series interrupting points needs to be approximately double that of one provided with two series interrupting points. The length becomes yet greater in circuit breakers of higher voltage classes.
U.S. Pat. No. 4,095,068 discloses a gas circuit breaker in which two interrupting units are arranged on different axes within a tank, whereby the interrupting units are juxtaposed in a manner to overlap structurally. With this circuit breaker, although the length in the direction of the switching operations of the interrupting units decreases to some extent, the diameter of the tank increases and the structure becomes complicated. The reason for this is that the current path becomes complicated because the two interrupting units are arranged in positions overlapping in the direction of the switching operations, which is undesirable in that they mutually exert influence of the gas having contributed to arc extinction. Another disadvantage is that the influences of electromagnetic forces increase.